Journal Article

Genotypic Variation of Rubisco Expression, Photosynthetic Electron Flow and Antioxidant Metabolism in the Chloroplasts of Chill-exposed Cucumber Plants

Yan-Hong Zhou, Jing-Quan Yu, Wei-Hua Mao, Li-Feng Huang, Xing-Shun Song and Salvador Nogués

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 47, issue 2, pages 192-199
Published in print February 2006 | ISSN: 0032-0781
Published online February 2006 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pci234
Genotypic Variation of Rubisco Expression, Photosynthetic Electron Flow and Antioxidant Metabolism in the Chloroplasts of Chill-exposed Cucumber Plants

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Genetic improvement of agronomic crops is necessary to cope with chilling stress. To identify the physiological factors responsible for this genotypic difference in chill-induced inhibition of photosynthesis, leaf CO2 assimilation, the electron flux in the chloroplast and the antioxidant metabolism in isolated chloroplasts were examined in two genotypes of cucumber (Cucumis sativus) plants with distinct chilling tolerance. Cucumber plants were exposed to 100 µmol m–2 s–1 at 9/7°C (day/night) for 10 d and were then returned to optimal conditions for 2 d. Chilling resulted in more significant reductions in rbcL and rbcS transcripts, ribulose-1,5-bisphosphate carboxylase-oxygenase (Rubisco) content and initial Rubisco activity, leading to higher electron flux to O2 in the chilling-sensitive genotype than in the chilling-tolerant genotype. The chilling-tolerant genotype showed lower H2O2 contents in the chloroplasts by maintaining higher H2O2-scavenging activity in the chloroplasts than in the chilling-sensitive genotype. H2O2 accumulation in chloroplast was negatively correlated with the initial Rubisco activity and photosynthetic rate.

Keywords: CO2 assimilation; Cucumis sativus; Electron transport flux; Reactive oxygen species; Rubisco; Water–water cycle; APX, ascorbate peroxidase; AsA, ascorbic acid; Asat, light-saturated rate of CO2 assimilation; DHAR, dehydroascorbate reductase; GR, glutathione reductase; Ja(O2-dependent), O2-dependent alternative electron flux; Ja(O2-independent), O2-independent alternative electron flux; Jc+o, electron flux for photosynthetic carbon reduction and photorespiratory carbon oxidation; JPSII, total electron flux in PSII; rbcL, large subunit of Rubisco; rbcS, small subunit of Rubisco; Rubisco, ribulose-1,5-bisphosphate carboxylase-oxygenase; ROS, reactive oxygen species; SOD, superoxide dismutase

Journal Article.  6848 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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